The present invention relates to optical measurements.
Optical time domain reflectometers (ODTR) are well known in the art and disclosed e.g. in U.S. Pat. No. 6,141,089, EP-A-872 721, or by Dennis Derickson in “Fiber optic test and measurement”, ISBN 0-13-534330-5,1998. In such ODTR, an optical stimulus signal with defined measuring wavelength is coupled into a fiber optical network, and a reflected and/or backscattered optical response signal is detected. The detected response signal is generally used for further analyses and visual representation.
With such ODTR measurements, faults occurring in the optical network to be measured can be detected even if occurring up to 200 km away from the ODTR.
Determining optical loss in reflected radiation in a fiber-optic light guide is known from U.S. Pat. No. 5,331,391. U.S. Pat. No. 5,724,127 discloses a microscopes for inspecting a fiber end.